diff --git a/orchagent/muxorch.cpp b/orchagent/muxorch.cpp
index eeae6b4cb2aa..4131b5a2357d 100644
--- a/orchagent/muxorch.cpp
+++ b/orchagent/muxorch.cpp
@@ -76,6 +76,7 @@ const map <string, MuxState> muxStateStringToVal =
 {
     { "active", MuxState::MUX_STATE_ACTIVE },
     { "standby", MuxState::MUX_STATE_STANDBY },
+    { "unknown", MuxState::MUX_STATE_STANDBY },
     { "init", MuxState::MUX_STATE_INIT },
     { "failed", MuxState::MUX_STATE_FAILED },
     { "pending", MuxState::MUX_STATE_PENDING },
@@ -396,6 +397,9 @@ void MuxCable::setState(string new_state)
 
     MuxState ns = muxStateStringToVal.at(new_state);
 
+    /* Update new_state to handle unknown state */
+    new_state = muxStateValToString.at(ns);
+
     auto it = muxStateTransition.find(make_pair(state_, ns));
 
     if (it ==  muxStateTransition.end())
diff --git a/tests/test_mux.py b/tests/test_mux.py
index c9aa578f7956..e9eb027a9d1b 100644
--- a/tests/test_mux.py
+++ b/tests/test_mux.py
@@ -433,6 +433,30 @@ def create_and_test_acl(self, appdb, asicdb, dvs, dvs_acl):
         self.set_mux_state(appdb, "Ethernet4", "active")
         dvs_acl.verify_no_acl_rules()
 
+        # Set unknown state and verify the behavior as standby
+        self.set_mux_state(appdb, "Ethernet0", "unknown")
+        sai_qualifier = self.get_expected_sai_qualifiers(["Ethernet0"], dvs_acl)
+        dvs_acl.verify_acl_rule(sai_qualifier, action="DROP", priority=self.ACL_PRIORITY)
+
+        # Verify change while setting unknown from active
+        self.set_mux_state(appdb, "Ethernet4", "unknown")
+        sai_qualifier = self.get_expected_sai_qualifiers(["Ethernet0","Ethernet4"], dvs_acl)
+        dvs_acl.verify_acl_rule(sai_qualifier, action="DROP", priority=self.ACL_PRIORITY)
+
+        self.set_mux_state(appdb, "Ethernet0", "active")
+        sai_qualifier = self.get_expected_sai_qualifiers(["Ethernet4"], dvs_acl)
+        dvs_acl.verify_acl_rule(sai_qualifier, action="DROP", priority=self.ACL_PRIORITY)
+
+        self.set_mux_state(appdb, "Ethernet0", "standby")
+        sai_qualifier = self.get_expected_sai_qualifiers(["Ethernet0","Ethernet4"], dvs_acl)
+        dvs_acl.verify_acl_rule(sai_qualifier, action="DROP", priority=self.ACL_PRIORITY)
+
+        # Verify no change while setting unknown from standby
+        self.set_mux_state(appdb, "Ethernet0", "unknown")
+        sai_qualifier = self.get_expected_sai_qualifiers(["Ethernet0","Ethernet4"], dvs_acl)
+        dvs_acl.verify_acl_rule(sai_qualifier, action="DROP", priority=self.ACL_PRIORITY)
+
+
     def create_and_test_metrics(self, appdb, statedb, dvs):
 
         # Set to active and test attributes for start and end time